1. Field of the invention
The present invention relates to an electrical particle gun enabling pulsed beams of particles to be generated and filtered according to their energy level.
2. Description of the prior art
Current electronic or ionic microlithographic techniques use pulsed electron or ion beams to etch circuits according to a reference design or diagram. For testing the circuits obtained in this way the particle beam has to be a pulsed beam with a high repetition frequency. Such pulsed beams are obtained by means of systems enabling transmission of the particle beam to be blocked or authorized. Currently used systems employ capacitor plates, resonant cavities or unipotential electrostatic lenses. Systems involving the use of unipotential electrostatic lenses are covered by publications including U.S. Pat. No. 4,439,685. In this system the unipotential lens is disposed after a first focussing lens of the focussing optical column held at the reference potential, so that the unipotential lens is totally separated from the source of electrical particles.
An object of the present invention is to provide a multifunction electrical particle gun enabling pulsed beams of electrical particles to be generated with a very high switching frequency.
Another object of the present invention is to provide an electrical particle gun enabling these electrical particles to be filtered according to their energy level to obtain a beam with reduced energy spread and/or pulsed emission at high switching frequencies.
A further object of the present invention is to provide an electrical particle gun that can be integrated into multistage accelerator systems.